Kdenlive has some tools for handling audio. Beside the audio spectrum viewer and some audio effects, you have following possibilities:
New in version 19.12.0.
The audio mixer has following function for each channel:
Channel number (audio track number) or Master channel
Mute an audio channel
Solo an audio channel
Record audio direct on the track of the related audio channel
Opens the effect stack of the related audio channel
Balance the audio channel. Either with the slider or with values
Adjustment of the volume
Multiple audio streams¶
New in version 20.08.0.
Multiple audio streams of a video clip. In clip properties on the tab audio you can adjust and manipulate each audio stream. More details see here Audio properties